SAN FRANCISCO – Too little sleep, especially early awakening, plays a significant role in raising unhealthy levels of inflammation among women with coronary heart disease, according to a new study.

Interestingly, the elevated inflammation affected only women, not men, even when adjusted for medical, lifestyle and socio-demographic differences, according to authors of the study, which appeared in the Journal of Psychiatric Research.1

The results were based on studies of patients at the San Francisco and Palo Alto VAMCs, the University of California San Francisco (UCSF) and nine public health clinics in the Community Health Network of San Francisco. Researchers suggest their findings, associated with the VA-funded Heart and Soul Study, beam a spotlight on important gender differences in cardiovascular health, providing evidence that inflammation might serve as a key biological pathway to the progression of heart disease in women.

“Inflammation is a well-known predictor of cardiovascular health,” said lead author Aric Prather, PhD, a clinical health psychologist and assistant professor of psychiatry at UCSF. “Now we have evidence that poor sleep appears to play a bigger role than we had previously thought in driving long-term increases in inflammation levels and may contribute to the negative consequences often associated with poor sleep.”

The study began in 2000 and involved nearly 700 participants with coronary heart disease, seeking to determine the association between self-reported sleep quality and changes in inflammation levels over five years in older people with stable coronary heart disease.

The average age of the male participants was 66, compared with age 64 among women. On average, however, the women had higher systolic blood pressure, were more likely to be taking antidepressants and were less likely than men to have a history of taking beta-blockers, statins or other medications that treat blood pressure and other coronary-related ailments.

Participants were asked when they first enrolled and five years later: “During the past month, how would you rate your overall sleep quality?” Their choices were “very good,” “fairly good,” “good,” “fairly bad,” or “very bad.”

Researchers found that poor sleep quality was significantly associated with five-year increases in the biomarkers Interleukin-6, C-reactive protein and Fibrinogen in women but not men: Women who reported very poor or fairly poor sleep quality showed a percent increase in markers 2.5 times that of men who said they slept poorly.

The association remained statistically significant after adjustment for characteristics such as lifestyle, medication use and cardiac function.

Because the women in the study were largely post-menopausal, researchers hypothesized that lower levels of estrogen could help explain the inflammatory activity associated with poor sleep. “It is possible that testosterone, which is at higher levels in men, served to buffer the effects of poor subjective sleep quality,” the authors wrote.

The study found that sleep problems were widespread, with about 81% of the women reporting that they frequently awakened, compared with 78% of men; that half the women said they woke too early, compared with almost 41% of the men; and that one-third of the women said they had difficulty falling asleep, compared with 31% of the men.